Okay, if you're not getting the GRUB menu, what are you getting?
Now, this might sound like it's too involved, but would you consider getting yourself a copy of
Ultimate Boot CD?
UBCD has some great boot mangers that I've used before to get into corrupted installs. At the very least, you'll have an awesome utilites CD that you can use for many other purposes.
The whole point of using UBCD would be to allow you to get into your FC5 installation, so that you repair/remake GRUB from there.